Gas distributing system



April 3, 1956 c. M. TENNEY, JR

GAS DISTRIBUTING SYSTEM Filed June 5, 1953 CHARLES M. TENNEY,JR

av 4P ATTORNEYS INVEN'T'OR United States Patent GAS DISTRIBUTING SYSTEMCharles M. Tenney, JL, Longmeadow, Mass. Application June 5, 1953,Serial No. 359,925 4 Claims. (Cl. 48-190) This invention relates to asystem for utilizing the high pressures of a natural gas pipe linefeeding into a local distribution system which is operated at lowerdistributing line pressures and for supplementing from time to timeduring periods of heavy demands on the local system the intake ofnatural gas with manufactured substitute gas or gas stored at lowerholder station pressures. The invention also relates to an economicaluse of auxiliary gas manufacturing facilities normally utilized only forsupplying locally available gas for a particular distribution system inthe event of a failure of the natural gas supply.

An object of the invention is to provide the means for an economicalusage of the pressures in a natural gas supply line to furnish power forfeeding a supplementary supply of manufactured gas into a localdistribution system at pressures suitable for the local system. Morespecifically the invention is designed to provide a more economicalmethod to introduce gas manufactured for local use at extremely lowpressures into the local lines at the required higher pressures for saidlocal distributing lines and in instances where the natural gas supplyline is fed into the system at initial pressures appreciably greaterthan said required local distributing line pressure.

As is well known in the trade natural gas is marketed by natural gaspipe line transmission companies according to a prescribed ratestructure in the calculation of which a dominant factor is the largestamount of gas or the peak load received by the local distributingcompany in any one daily period during the year. Accordingly a localdistributing system may maintain an auxiliary supply of manufactured orstorage gas, not only for maintaining service to users in the event of aserious failure of the natural gas supply, but also to feed manufacturedgas into its lines to mix with the natural gas whenever it appearsduring periods of heavy demand that a daily amount of natural gas takenin will be excessively high. This is known as peak shaving and operatesby the in troduction of a locally produced supply during periods ofexcessive demands to level off the intake of natural gas and thus moreequitably average out the rate factor determined by the largest dailyamount received.

When gas is manufactured locally or held in reserve at holder stationsthe pressures are of course, relatively low and must be raised fortransmission through the local distribution lines to the point of use.Compressors suitably driven by an outside source are commonly used tocompress the gas to the required pressures. this invention is to utilizethe power from the high pressure natural gas intake lines and, in lieuof simply reducing the pressures at the intake by exhausting the same,to drive one or more compressors to raise the pressure of the localsupply lines and to collect the exhaust natural gas of the drivers,proportion, and mix it with all or part of the locally produced gas anddistribute the mixture into the local lines. It will be realized thatthe amount of local gas to be compressed will be determined by the poweravailable through the expansion of the local systems lowest pressurenatural gas requirements. Thus in particular systems where the expansionof natural gas through turbo-compressor units will not supply asufficient concentration of local gas at the required pressures for theneeds of the system, additional or auxiliary power may need to be addedeither by steam, electric, diesel or gas combustion engines.

An object of 2,740,701 Patented Apr. 3, 1956 The above and other objectsand advantages of the invention will be apparent from the followingdescription thereof in connection with the accompanying drawing showinga diagrammatic representation of a distributing system in which naturalgas is utilized and wherein the system supplies its gas at severalpressures each being higher than holder or other local source pressure.

Referring to the drawing a valved natural gas intake line 1 is shown atthe left feeding into an inlet header 2 where the incoming natural gasfor the system is delivered at a relatively high pressure as, forexample, p. s. i. g. Attached to the header 2 are a pair of inlet lineshaving suitable flow-controlled pressure regulators with inlet andoutlet valves as indicated at 3 and 4 and a pair of lines havingpressure regulators as at 5 and 6. The regulators at 3 and 4 may beadapted to reduce the natural gas to one pressure, for example, 10 p. s.i. g., required for local distribution through a pipe 7; and theregulators at 5 and 6 may be adapted to reduce the natural gas to asecond pressure required for distribution in the system through pipe 8as for example 40 p. s. i. g. The balance of the systems natural gasrequirements may be fed from header 2 to power a pair of natural gasdriven turbocompressor units through pipes 9 and 10. The turbine driversof the compressor units are indicated at 11 and 12. The exhaust lines 13and 14 for drivers 11 and 12 are connected by an exhaust gas header 15.The turbines may be suitably adapted to operate either by natural gasunder pressure or by steam pressure. The compressors may be of anysuitable type such as a rotary positive-pressure compressor. An inletsubstitute gas line 16 from a holder source or from a source of locallymanufactured gas is connected to the inlet side of the compressor 17powered by driver 11 by a branch line 18, and is connected directly tothe compressor 19 of the driver 12. The inlet source line of the locallysubstituted gas is supplied at a pressure lower than that required fordistribution in the system and may be, for example, at a pressure of Ap. s. i. g.

The outlet lines of the compressed local gas are at 20 and 21 andassuming in the example being given that the requirements of the systemare for distribution as through lines 7 and 8 of gas at pressures of l0p. s. i. g. and 40 p. s. i. g., respectively, as above mentioned, thelocally supplied gas is to be raised from the inlet pressure of k p. s.i. g. in lines 18 and 16 to an outlet pressure in lines 20 and 21 of 10p. s. i. g. and 40 p. s. i. g. The natural gas and substitute gas inlines 7 and 20 at 10 p. s. i. g. are mixed by suitable means as will bedescribed. The natural and substitute gas in lines 8 and 21 at 40 p. s.i. g. may be similarly mixed for passing into the local distributingsystem.

The natural gas admitted at 90 p. s. i. g. to the turbine drivers 11 and12 is exhausted into the common discharge header 15 and header 15 isconnected with the natural gas line 7 by a pipe 22 having an exhaustvalve 23. The pressure of the exhaust natural gas in header 15 andconnector 22 is maintained at 10 p. s. i. g. by reason of the 10 p. s.i. g. pressure maintained in. line 7 by the flow controlled pressureregulators 3 and 4. Thus the exhaust natural gas is fed back into thesystem at the required pressure for the local distribution line 7.

Heat exchangers 25 and 26 for pipes 9 and 10 are provided for raisingthe temperature of the natural gas passing to the turbines 11 and 12from header 2. The source of heat for the exchangers may be live steamfrom steam headers 27 and 28 through connector pipes 29 and 30. Controlvalves 31 and 32 govern the amount of steam required to heat theincoming high pressure natural gas to a temperature sufficient to passthrough the turbines and into the exhaust lines 13 and 14 at a constantexhaust temperature, for example at 60 F., regardless of the quantity ofnatural gas passing through the turbine. The amount of steam required tokeep the exhaust natural gas temperature constant may be regulatedthrough a conventional control line for each exchanger as indicated at33 and 34.

The steam headers 27 and 28 also feed into the lines 9 and 10 and arefor operating the turbines 11 and 12 in the event of a total natural gasfailure or in the event a higher concentration of locally manufacturedgas is required than can be produced by the existing energy balance. Fornormal operation live steam inlet valves and 36 are closed for drivingthe turbines by the high pressure natural gas in lines 9 and 10. Fordriving the turbines by steam, inlet valves 37 and 38 are closed againstthe natural gas inlet supply and outlet valves 39 and 4! are also closedin the natural gas exhaust header 15. The steam inlet valves 35 and 36are opened on the live steam inlet side and steam exhaust valves 41 and42, normally closed, are opened to exhaust the steam from the turbines.

Thus the turbines may be driven by live steam during periods oiemergency when the natural gas supply has failed for any reason.

Throttle valves 43 and 44 at the inlet sides of turbines it and 12 arefor maintaining the required pressure of 10 p. s. i. g. and p. s. i. g.in the compressor outlet lines 20 and 21 being regulated by conventionalcontrol lines 45 and 46 sensitive to the pressures in lines 20 and 21 asindicated. The compressors are provided with the suitable inlet andoutlet valves indicated at 47 and 48 respectively for both units, asuitable check valve 49 also being placed on the discharge side in eachinstance.

From the above it will be seen that the incoming natural gas at the highpressure at which it is received is thus utilized to drive a pair ofturbo-compressor units for raising the pressure of locally manufacturedor stored gas to the requirements of the local distributing system. Theexample of the local system as shown requires ditierent pressures in twodistributing lines. It may, of course, be adapted for a system requiringbut one distributing line at a given pressure lower than the natural gasinlet pres sure and may also be adapted to operate in a system wheremultiple pressures are required.

In the example of the drawing the lines 7 and 20 of natural and locallyproduced gas at 10 p. s. i. g. and lines 3 and 21 at 40 p. s. i. g. aremixed in any conventionally arranged manner, the system shown havingconventional ratio control devices at 50 connected between lines 7 and20 and 8 and 21. In lines 7 and 8 conventional orifice meters 51 areprovided with inlet and outlet valves 52 :md 53 and lay-pass lines 54with by-pass valves 55. These units meter the total requirements of thesystems natural gas requirements coming through lines 7 and 8.

The outlet end of each local gas outlet line 20 and 2? is connected tonatural gas lines 7 and 8 by a mixing T as at 56. Beyond the T the mixednatural and local gases ass through the district regulators 57 in theusual fashion and out into the distribution system through lines 58 and59.

For checking the richness of the mixed gases gravity recorders 60 may belocated in the inlet line 1 of the natural gas, in the inlet line 16 ofthe substitute gas and in the mixed gas system lines 58 and 59. Thespecific gravilies may thus be compared for determining any neccssaryadjustments in the system.

The system shown may be adapted for the introduction of natural gasalone directly into the system when no locally substituted gas isrequired; for the introduction oi prescribed quantities of local gas asmay be desired for shaving the natural gas intake load during periodswhen an abnormal daily peak load may be anticipated; and for auxiliaryoperation to distribute local gas entirely when the natural gas supplyis interrupted for any reason.

What is claimed is:

1. In combination with a natural gas pipe line inlet fit! (ill

header through which natural gas is received by a local distributingsystem at a higher pressure than the pressures required for saiddistributing system and a substitute gas inlet line in which a localreserve supply of gas is carried at a pressure lower than said requireddistributing pressure, means for utilizing the higher pressure of thenatural gas line to raise the pressure of said local supply to saidrequired local distributing pressures and distribution into the systemmixed with said natural gas, said means including a turbo-compressorunit with the natural gas inlet header ronncctcd to the inlet side ofthe driver thereof and the said inlet of the local supply line beingconnected to the compressor inlet, an exhaust line at the outlet side ofsaid driver element and a natural gas feeder line communicatingtherewith and with said inlet header with flow controlled pressurereducing means to maintain the pressure in said feeder line and exhaustline at a required local distributing pressure, a discharging line atthe outlet of the compressor for delivery of said local gas supply atthe required distributing pressure, and said compressor discharge andfeeder lines being united with gas mixer means therebetwcen forcontrolling the ratio of mixed natural and local gases for passage intosaid local distributing system.

2. The combination of claim 1 in which said natural gas inlet line isprovided with heating means to raise the temperature of said incomingnatural gas and heat input regulating means to supply said heating meanshaving a control sensitive to the temperature of said natural gases atthe exhaust side of said driver element to control said heater means.

3. The combination of claim 2 in which said inlet line to the driverelement is provided with a throttle valve having a control sensitive tothe pressures in said compressor discharge line for regulating the rateof natural gas passing to said driver.

4. in combination with a natural gas pipe line inlet through whichnatural gas is received by a local distributing system at a higherpressure than the pressures required for said distributing system, asubstitute gas inlet line in which a local reserve supply of gas iscarried at a pres sure lower than said required distributing pressuresand means for utilizing the higher pressure of the natural gas line toraise the pressure of said local supply to said required localdistributing pressures and distribution into the system mixed with saidnatural gas, said means comprising a pair of turbo-compressor units witha natural gas inlet header connected to the inlet sides of the driversthereof, said inlet of the local supply line being connected to thecompressor inlets, a natural gas feeder line connected to said naturalgas inlet header and having fiowcontrolled pressure reducing meansadapted to admit natural gas thereto at one pressure and a secondnatural gas feeder line similarly connected to said natural gas inletheader and having flow-controlled pressure reducing rue-ans adapted toadmit natural gas thereto at a lower pressure. a natural gas exhaustheader connected to the outlet sides of said unit driver elements havingan outlet joined to said second feeder line, the discharge line of oneof said compressors being connected to said first feeder line for delivery of locally supplied gas at said first feeder line pres sure withratio control means therebetween for governing the mixture of gases atsaid connection, the discharge line of the other compressor having acontrolled mixer connection with said second feeder line for mixing thelocal and natural, gases at the lower pressure beyond the connection ofsaid second feeder with said exhaust header.

References Cited in the file or this patent UNITED STATES lATljllTE1,873,045 Saathoff Aug. 23, i932 2,392,783 Stevens Ian. 8, 1946 2.631331Shaelfer et a1 Mar. 17, 1953 2,640,768 MacSporran June 2, 1953 2,676,876Mosely -2 Apr. 27, 1954

1. IN COMBINATION WITH A NATURAL GAS PIPE LINE INLET HEADER THROUGHWHICH NATURAL GAS IS RECEIVED BY A LOCAL DISTRIBUTING SYSTEM AT A HIGHERPRESSURE THAN THE PRESSURES REQUIRED FOR SAID DISTRIBUTING SYSTEM AND ASUBSTITUTE GAS INLET LINE IN WHICH A LOCAL RESERVE SUPPLY OF GAS ISNATURAL AT A PRESSURE LOWER THAN SAID REQUIRED DISTRIBUTING PRESSURE,MEANS FOR UTILIZING THE HIGHER PRESSURE OF THE NATURAL GAS LINE TO RAISETHE PRESSURE OF SAID LOCAL SUPPLY TO SAID REQUIRED LOCAL DISTRIBUTINGPRESSURES AND DISTRIBUTION INTO THE SYSTEM MIXED WITH SAID NATURAL GAS,SAID MEANS INCLUDING A TURBO-COMPRESSOR UNIT WITH THE NATURAL GAS INLETHEADER CONNECTED TO THE INLET SIDE OF THE DRIVER THEREOF AND THE SAIDINLET OF THE LOCAL SUPPLY LINE BEING CONNECTED TO THE COMPRESSOR INLET,AN EXHAUST LINE AT THE OUTLET SIDE OF SAID DRIVER ELEMENT AND A NATURALGAS FEEDER LINE COMMUNICATING THEREWITH AND WITH SAID INLET HEADER WITHFLOW CONTROLLED PRESSURE REDUCING MEANS TO MAINTAIN THE PRESSURE IN SAIDFEEDER LINE AND EXHAUST LINE AT A REQUIRED LOCAL DISTRIBUTING PRESSURE,A DISCHARGING LINE AT THE OUTLET OF THECOMPRESSOR FOR DELIVERY OF SAIDLOCAL GAS SUPPLY AT THE LIQUID DISTRIBUTING PRESSURE, AND SAIDCOMPRESSOR DISCHARGE AND FEEDER LINES BEING UNITED WITH GAS MIXER MEANSTHEREBETWEEN FOR CONTROLLING THE RATIO OF MIXED NATURAL AND LOCAL GASESFOR PASSAGE INTO SAID LOCAL DISTRIBUTING SYSTEM.